Head bolt Torqueing

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History
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Joined: Tue May 05, 2015 8:03 pm

Re: Head bolt Torqueing

#11 Post by History » Tue Jun 30, 2015 9:21 pm

I gave an inadequate answer.

I said that when I assemble bolts etc I oil the threads. This is for general stuff. But some fixings such as head bolts may be required to be dry. Depends on what the makers say.
On less ambitious engines such a A series BMC the main thing is that head nuts are all the same torque. If an A series is torqued to say 60 ftlbs then if only done to 55 it will be OK. Obviously its best to go by what BMC say. In the case of A series it wouldn't make much difference if dry or oiled.

By general stuff I mean bolts that hold the headlights in etc. Not important stuff ĺike big ends.

Car makers often don't state whether dry or oiled. My car's workshop manual has default torque settings which go by the bolt size and thread. Only ones not listed are wood screws and self tappers.

Putting engines together and keeping oil off threads is awkward.

A much more important thing to look out for is oil in blind threaded holes. The stud or bolt can hydraulic the component and crack it.

The wheel nuts on my car ard phosphor bronze and should be oiled and tortured to 50lbs.

Steel road wheels when torqued up slightly spring in around the nut. This helps the nut stay tight.
Aluminum alloy wheels don't have this feature so extra care is needed.
Incidently if a bolt is torqued up with a click torque wrench and then checked later as mechanics tend to do then each time the wrench clicks the bolt goes slightly tighter and its possible to add say 5ftlb with out realising. On an A series it won't matter. But some engines are fussy buggers.

I use a bendy arm wrench. They don't need calibrating.

Dashed bad luck with paint in the wheel holes.
Thats racing for you.

A good indication of how tight a wheel nut should be is the lenght of the factory supplied wheel nut wrench.

harvey
Posts: 286
Joined: Wed Jan 05, 2011 4:47 pm

Re: Head bolt Torqueing

#12 Post by harvey » Wed Jul 01, 2015 1:45 pm

History wrote: Incidently if a bolt is torqued up with a click torque wrench and then checked later as mechanics tend to do then each time the wrench clicks the bolt goes slightly tighter and its possible to add say 5ftlb with out realising.
In the case of wheelnuts, if you're re-checking then they should be backed off and retorqued. Same goes for cylinder heads.
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.

History
Posts: 365
Joined: Tue May 05, 2015 8:03 pm

Re: Head bolt Torqueing

#13 Post by History » Wed Jul 01, 2015 7:14 pm

Except so called stretch bolts. Depends on what the car maker says.

It is possible for a wheel nut to seize and give a correct torture reading, without actually clamping the wheel to the hub with sufficient clamping pressure.

At the police garage we had special extension bars that fitted to a windy gun. The bars limited the torque. I saw no point because after I used a torque wrench.

On all cast iron engines the torque of the bolts or nuts is not so important. I have many times used my sense of torque without problems. Head not ends etc.

They ( not me I don't know) reckon that oiled is 15 to 25% tighter.

Bob

jonnyhahn
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Joined: Fri Jun 12, 2015 7:55 pm

Re: Head bolt Torqueing

#14 Post by jonnyhahn » Sun Jul 05, 2015 11:23 am

After what you told me I'm guessing it's a vacuum leak somewhere? The car doesnt have a cam position sensor or a maf sensor. I've been slowly working through all the fuel lines and vacuum likes checking for splits and good connections so I'll let you know, if that doesn't work then it's on to checking the loom!

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TerryG
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Location: East Midlands

Re: Head bolt Torqueing

#15 Post by TerryG » Sun Jul 05, 2015 11:25 am

Does it have a manifold pressure sensor? that is used on (some) turbo cars to do the same job as a MAF.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.

jimmyybob
Posts: 352
Joined: Wed Jan 05, 2011 8:59 pm

Re: Head bolt Torqueing

#16 Post by jimmyybob » Wed Jul 08, 2015 9:20 pm

One of the other fiat/lancia engines needed 30lbft then 60lbft THEN the 90+90, i can tell you that makes your bum cheeks nip a bit.

Im assuming you have the 8 valve engine.?

Did you take off the inlet or exhaust cambox.?

A couple of things spring to mind, its easy to mix up the Vac pipes of these engines and few of the electrical sockets are also interchangeable.
My immediate though would be the crank position sensor usually a white wire on this engine they fail if you sneeze on them, you can check it with an Ohm meter but i cant remember the measurement.
Distributor pickups fail as well but depends on the type fitted.

It would be helpful to know how far you stripped it and wether it was inlet or exhaust.

Do you have the flatter rocker covers or the boxy ones.?

History
Posts: 365
Joined: Tue May 05, 2015 8:03 pm

Re: Head bolt Torqueing

#17 Post by History » Wed Jul 08, 2015 10:25 pm

By rule of thumb.
when testing sensors with digital ohm meter infinity means no good and dead short means no good. So a quick test with an ohm meter without knowing the actual ohms its meant to be is possible.

Bring back carbs and points.

Bob.

jonnyhahn
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Joined: Fri Jun 12, 2015 7:55 pm

Re: Head bolt Torqueing

#18 Post by jonnyhahn » Tue Sep 01, 2015 3:14 pm

Hi again guys,
never got back to you all but the small niggling problems continue. Got the engine started afterwards, the only fault I found was the inlet air sensor, the connections had pushed back on the plug so there wasn't a connection. I sorted that and it fire up straight away. But now I have a new problem. When driving if you take your foot off the accelerator the RPM stick at about 2000RPM. It also does this when changing gear even if the engine is below 2000 when changing gear it shoots up. Then when you come up to a red light it will jump up to 2000RPM and you have to rev it for it to go back down to a normal idle speed and it will ever so slowly climb to 2000 again. Occasionally as well it will pulse on idle around the correct idle speed.
Thanks again guys!

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TerryG
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Location: East Midlands

Re: Head bolt Torqueing

#19 Post by TerryG » Tue Sep 01, 2015 5:07 pm

2 things spring to mind, either the butterfly is sticking so holding the throttle slightly open or your TPS has a dead spot at idle. Both easy to check, pop the intake hose off and watch the butterfly is returning closed every time you let go of the throttle. to check the TPS put a meter on ohms across it, make sure that it is within the tolerance in the manual and that the resistance is a smooth sweep.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.

jonnyhahn
Posts: 7
Joined: Fri Jun 12, 2015 7:55 pm

Re: Head bolt Torqueing

#20 Post by jonnyhahn » Tue Sep 01, 2015 11:26 pm

TerryG wrote:2 things spring to mind, either the butterfly is sticking so holding the throttle slightly open or your TPS has a dead spot at idle. Both easy to check, pop the intake hose off and watch the butterfly is returning closed every time you let go of the throttle. to check the TPS put a meter on ohms across it, make sure that it is within the tolerance in the manual and that the resistance is a smooth sweep.
Awesome! i will check them both when I'm home at the weekend. I just noticed your located in east midlands. where abouts do you live?

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